Polyurethane-based metal monatomic catalyst and preparation method thereof
By anchoring metal single atoms in the polyurethane structure, the polyurethane-based metal single atom catalyst is prepared, which solves the problems of existing catalyst stability and low recovery, and realizes the efficient cycloaddition reaction between CO2 and epoxide, which is suitable for industrial applications.
Patent Information
- Application Number
- CN202510002396.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-02
- Publication Date
- 2025-05-27
AI Technical Summary
The existing heterogeneous CO2 cycloaddition catalysts have problems such as poor stability and low recovery, which leads to a reduced yield of cyclic carbonate and a high production cost in the cyclic reaction.
Through a simple one-step glue connection method, metal single atoms are anchored in the polyurethane structure to prepare a polyurethane-based metal single atom catalyst, achieving high activity, selectivity and stability of catalytic CO2 and epoxide synthesis of cyclic carbonate.
The catalyst exhibits high activity, high selectivity and excellent stability under mild conditions, and is easy to recover and reuse, which significantly reduces the cost of downstream product separation and purification, and is suitable for industrial production.
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Figure CN120037975A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of organic synthesis, and particularly relates to a polyurethane-based metal single-atom catalyst and a preparation method thereof. Background Art
[0002] At present, the excessive emission of CO 2 is one of the important reasons for global warming. How to reasonably reduce the excessive CO 2 in the atmosphere is a daunting challenge faced by scientists. Converting CO 2 into high-value industrial chemicals is regarded as an ideal solution. Among them, the preparation of cyclic carbonates by the addition reaction of CO 2 and epoxides is a very important green carbon resource conversion technology (100% carbon utilization rate), and its products can be widely used in polar solvents, pharmaceutical intermediates and lithium battery electrolytes.
[0003] So far, researchers have studied a large number of homogeneous and heterogeneous catalysts for the synthesis of cyclic carbonates. Compared with traditional homogeneous catalysts, heterogeneous CO 2 cycloaddition catalysts (mainly powder catalysts) eliminate the cumbersome product separation and purification steps and improve the economic feasibility of the process, but still face the problems of low catalytic stability and recovery rate. Among many heterogeneous catalysts, single-atom catalysts have higher atomic utilization rate, uniform active site distribution and are easy to design well-defined Lewis acid-base active sites, making the CO 2 cycloaddition reaction have higher catalytic activity. At present, many single-atom catalysts have been reported for the CO 2 cycloaddition reaction, but still face a series of problems such as a significant decrease in the yield of cyclic carbonates and poor stability in the recycling reaction, which can be attributed to the high free energy of metal single atoms on the catalyst surface, which is easy to agglomerate and deactivate during the reaction process. Therefore, there is an urgent need to develop a single-atom catalyst with excellent stability and easy recovery to meet the industrial requirements of the CO 2 cycloaddition reaction.
[0004] As a new type of catalyst material, polyurethane has shown great application prospects in the field of energy catalysis due to its stable chemical properties, designable chemical structure and simple and inexpensive preparation process. Further, the organic combination of metal single atoms and polyurethane materials to prepare a new type of highly stable single-atom catalyst is a very promising idea, which is expected to solve the problems of low stability, low recovery rate and high production cost of current heterogeneous CO 2 cycloaddition catalysts. Summary of the Invention
[0005] The key technical problem to be solved by the present invention is to provide a catalyst with a simple synthesis method, low process cost, easy recovery and high reuse rate. The catalyst can catalyze CO with high activity, high selectivity and high stability under mild (low temperature and normal pressure) and solvent-free conditions. 2 Synthesize cyclic carbonates with epoxides to gradually achieve the goal of treating CO in the atmosphere 2 Efficient resource utilization.
[0006] The present invention provides a method for preparing a polyurethane-based metal single atom catalyst, wherein the metal single atom is anchored in the polyurethane structure by a simple one-step bonding method to prepare a polyurethane catalyst having excellent CO 2 A polyurethane-based metal single atom catalyst with cycloaddition performance comprises the following steps:
[0007] (1) dissolving an appropriate amount of metal precursor and triethanolamine in an organic reagent to obtain solution A;
[0008] (2) dissolving an appropriate amount of p-phenylene diisocyanate in an organic reagent to obtain a solution B;
[0009] (3) Under the protection of inert gas, solution A and solution B are fully mixed and stirred at a constant temperature until gelation occurs. Stirring is stopped and the mixture is quickly transferred to a mold for shaping. Subsequently, the gel is subjected to a constant temperature aging treatment to further improve its mechanical strength.
[0010] (4) After gel aging, the excess organic reagent on the catalyst surface is removed to obtain polyurethane-based metal single atom catalysts (M-PU) of various shapes;
[0011] (5) Place the dried M-PU in a reactor, add an appropriate amount of epoxide substrate and co-catalyst, and continuously introduce CO 2 The gas was used to replace the air in the reaction system, and then CO 2 Cyclic carbonates were prepared by cycloaddition with epoxides. After the reaction was completed, the reaction system was cooled to room temperature, and M-PU was directly taken out and washed three times with deionized water and anhydrous ethanol to achieve recovery and reuse. The liquid product was qualitatively and quantitatively analyzed by gas chromatography and nuclear magnetic resonance, and the conversion rate of epoxides, the yield and selectivity of the target product cyclic carbonate were further calculated.
[0012] Among them, CO at normal pressure 2 The reaction equation for preparing cyclic carbonate by cycloaddition with epoxide is as follows:
[0013]
[0014] The synthesis process and structural diagram of the polyurethane-based metal single atom catalyst are as follows:
[0015]
[0016] Preferably, in step (1), the metal types include, but are not limited to, Au, Ag, Cu, Ni, Pd, Pt, Co, Zn, Ti, Fe, Ru, Mo, Al, Mg; the metal precursor types include, but are not limited to, metal oxides, metal chlorides, carbonates, sulfates, acetates; the concentration of the metal precursor is 0.001 - 1 mol / L; the concentration of triethanolamine is 0.01 - 10 mol / L.
[0017] Preferably, in step (2), the concentration of p-phenylene diisocyanate is 0.01 - 10 mol / L.
[0018] Preferably, in steps (1) and (2), the organic reagent includes, but is not limited to, a mixture of one or more organic reagents, and the types of organic reagents include, but are not limited to, acetonitrile, tetrahydrofuran, 1,4-dioxane, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, acetone.
[0019] Preferably, in step (3), the inert gas includes, but is not limited to, argon, nitrogen, helium; the temperature for constant-temperature stirring is 10 - 90 °C, the stirring rate is 50 - 1000 rpm, and the stirring time is 5 - 1200 s; the temperature for constant-temperature aging is 10 - 90 °C, and the gel time is 1 - 100 h.
[0020] Preferably, in step (4), the method for removing the organic solvent on the surface of the catalyst includes, but is not limited to, volatilization at room temperature and normal pressure, vacuum drying, air drying, freeze drying; the shape of the catalyst includes, but is not limited to, block, sheet, strip, film; the size of the catalyst is: 1 - 100000 cm 2 。
[0021] Preferably, in step (5), the types of epoxides include, but are not limited to, ethylene oxide, propylene oxide, epichlorohydrin, epibromohydrin, styrene oxide, 1,2-epoxybutane; the types of cocatalysts include, but are not limited to, tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride, tetrabutylammonium iodide; the addition amount of the cocatalyst is 0.05 - 5.0 mmol; the introduced CO 2 gas includes, but is not limited to, high-purity (100%) CO 2 、low-purity (0.01 - 15%) CO 2 、air, industrial flue gas; the mild reaction conditions are low temperature and normal pressure, the temperature is 20 - 100 °C, and the reaction time is 2 - 40 h.
[0022] The present invention also provides a polyurethane-based metal single-atom catalyst prepared by the above preparation method.
[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0024] (1) The synthesis method of the polyurethane-based metal single-atom catalyst provided by the present invention has the advantages of mild conditions, simple equipment, convenient operation, etc., avoiding the disadvantages such as high temperature, high energy consumption, and cumbersome preparation process in the preparation process (high-temperature calcination synthesis) of traditional metal single-atom catalysts.
[0025] (2) The preparation process of the polyurethane-based metal single-atom catalyst provided by the present invention is flexible, and catalysts of different sizes and shapes (blocky, strip-shaped, sheet-shaped, film-shaped, etc.) can be prepared according to actual needs. After the reaction ends, it can be directly taken out and reused, with excellent structural stability and catalytic stability.
[0026] (3) The polyurethane-based metal single-atom catalyst provided by the present invention can be used to synthesize high-purity cyclic carbonates (selectivity ≥ 99.0%) with low-concentration CO 2 and different types of epoxides. Combining the advantages of simple preparation process, easy separation and recovery, and high catalytic selectivity of this catalyst, this reaction system greatly reduces the cost of downstream product separation and purification, and is more conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 It is a physical picture of the polyurethane-based catalyst synthesized in Examples 1-4.
[0028] Figure 2 It is an AC-HAADF-STEM picture of Pd-PU prepared in Example 1.
[0029] Figure 3 It is a TEM picture and an EDS picture of Pd-PU prepared in Example 1.
[0030] Figure 4 It is a TEM picture and an EDS picture of Co-PU prepared in Example 2.
[0031] Figure 5 It is a TEM picture and an EDS picture of Ni-PU prepared in Example 4.
[0032] Figure 6 It is the recycling performance of Pd-PU prepared in Example 1. DETAILED DESCRIPTION OF THE INVENTION
[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0034] Example 1:
[0035] (1) Ultrasonically disperse 0.1 mmol of palladium acetate and 5 mmol of triethanolamine in 5 mL of DMF to obtain solution A;
[0036] (2) Ultrasonically disperse 6 mmol of p-phenylene diisocyanate in 15 mL of DMF to obtain solution B;
[0037] (3) Under an Ar atmosphere, fully mix solution A and solution B, stir at a constant temperature of 30 °C until gelation occurs, stop stirring and quickly transfer it to a centrifuge tube for shaping. Subsequently, the gel is aged at a constant temperature of 30 °C in an oven for 24 h;
[0038] (4) Further, place the aged gel in a vacuum oven at 60 °C to remove excess organic reagents to obtain a bulk polyurethane-based Pd single-atom catalyst (Pd-PU);
[0039] (5) Place the dried Pd-PU in a reaction kettle, add 5 mL of epichlorohydrin and 0.1 mmol of TBAB, and continuously introduce CO 2 gas with a purity of 100% to displace the air in the system (maintaining atmospheric pressure). Subsequently, seal it and raise the temperature to 50 °C to start the reaction for 8 h. After the reaction is completed, wait for the reaction system to cool to room temperature, directly take out the Pd-PU, wash it three times with deionized water and anhydrous ethanol, and dry it in a vacuum oven at 60 °C for 3 h before performing cyclic tests. The liquid-phase products are qualitatively and quantitatively analyzed by gas chromatography. The results show that the conversion rate of epichlorohydrin is 99.8%, and the product selectivity is as high as 99.6%. After 20 cyclic tests, Pd-PU still exhibits a substrate conversion rate of 91.3% and a product selectivity of 99.3%.
[0040] Example 2:
[0041] (1) Ultrasonically disperse 0.15 mmol of cobalt acetate and 5 mmol of triethanolamine in 5 mL of DMF to obtain solution A;
[0042] (2) Ultrasonically disperse 6 mmol of p-phenylene diisocyanate in 10 mL of DMF to obtain solution B;
[0043] (3) Under an Ar atmosphere, fully mix solution A and solution B, stir at a constant temperature of 30 °C until gelation occurs, stop stirring and quickly transfer it to a centrifuge tube for shaping. Subsequently, the gel is aged at a constant temperature of 50 °C in an oven for 24 h;
[0044] (4) Further, place the aged gel in a vacuum oven at 60 °C to remove excess organic reagents to obtain a bulk polyurethane-based Co single-atom catalyst (Co-PU);
[0045] (5) Place the dried Co-PU in a reaction kettle, add 5 mL of styrene oxide and 0.1 mmol of TBAB, and continuously introduce CO with a purity of 100% 2 gas to displace the air in the system (maintaining normal pressure). Then, seal the system and raise the temperature to 70 °C to start the reaction for 8 h. After the reaction is completed, wait for the reaction system to cool to room temperature, directly take out the Co-PU, wash it three times with deionized water and absolute ethanol, and dry it in a vacuum oven at 60 °C for 3 h before it can be recycled. The liquid-phase product was qualitatively and quantitatively analyzed by gas chromatography. The results showed that the conversion rate of styrene oxide was 95.7%, and the product selectivity reached 99.1%.
[0046] Example 3:
[0047] (1) Ultrasonically disperse 0.1 mmol of zinc chloride and 4 mmol of triethanolamine in 5 mL of DMF to obtain solution A;
[0048] (2) Ultrasonically disperse 6 mmol of p-phenylene diisocyanate in 10 mL of DMF to obtain solution B;
[0049] (3) Under an Ar atmosphere, fully mix solution A and solution B, stir at a constant temperature of 30 °C until gelation occurs, stop stirring and quickly transfer it to a centrifuge tube for shaping. Subsequently, the gel was aged at a constant temperature of 50 °C in an oven for 24 h;
[0050] (4) Further, place the aged gel in a vacuum oven at 60 °C to remove the excess organic reagent to obtain a bulk polyurethane-based Zn single-atom catalyst (Zn-PU);
[0051] (5) Place the dried Zn-PU in a reaction kettle, add 5 mL of propylene oxide and 0.5 mmol of TBAB, and continuously introduce CO with a purity of 100% 2 gas to displace the air in the system (maintaining normal pressure). Then, seal the system and raise the temperature to 30 °C to start the reaction for 5 h. After the reaction is completed, wait for the reaction system to cool to room temperature, directly take out the Zn-PU, wash it three times with deionized water and absolute ethanol, and dry it in a vacuum oven at 60 °C for 3 h before it can be recycled. The liquid-phase product was qualitatively and quantitatively analyzed by gas chromatography. The results showed that the conversion rate of propylene oxide was 99.7%, and the product selectivity reached 99.5%.
[0052] Example 4:
[0053] (1) Ultrasonically disperse 0.15 mmol of nickel nitrate and 5 mmol of triethanolamine in 5 mL of DMF to obtain solution A;
[0054] (2) Ultrasonically disperse 6 mmol of p-phenylene diisocyanate in 10 mL of DMF to obtain Solution B;
[0055] (3) Under an Ar atmosphere, thoroughly mix Solution A and Solution B, stir at room temperature until gelation occurs, stop stirring and quickly transfer to a centrifuge tube for shaping. Subsequently, the gel is aged at a constant temperature of 70 °C in an oven for 24 h;
[0056] (4) Further, place the aged gel in a vacuum oven at 60 °C to remove excess organic reagents to obtain a bulk polyurethane-based Ni single-atom catalyst (Ni-PU);
[0057] (5) Place the dried Ni-PU in a reaction kettle, add 5 mL of propylene oxide and 0.1 mmol of TBAB, and continuously introduce CO gas with a purity of 100% 2 to displace the air in the system (maintaining normal pressure). Subsequently, seal and raise the temperature to 30 °C to start the reaction, and react for 8 h. After the reaction is completed, wait for the reaction system to cool to room temperature, directly take out the Ni-PU, wash it three times with deionized water and anhydrous ethanol, and dry it in a vacuum oven at 60 °C for 3 h before it can be reused. The liquid-phase product is qualitatively and quantitatively analyzed by gas chromatography. The results show that the conversion rate of propylene oxide is 96.7%, and the product selectivity reaches 99.2%.
[0058] Example 5:
[0059] The preparation process and experimental operation steps of Pd-PU are the same as those in Example 1. Replace high-purity CO 2 (100%) with industrial simulated flue gas (15% CO 2 + 85% N 2 ), and extend the reaction time to 25 h. The results show that the conversion rate of epichlorohydrin is 90.4%, and the product selectivity reaches 99.5%.
[0060] Example 6:
[0061] The preparation process and experimental operation steps of Zn-PU are the same as those in Example 3. Replace high-purity CO 2 (100%) with industrial simulated flue gas (15% CO 2 + 85% N 2 ), and extend the reaction time to 20 h. The results show that the conversion rate of propylene oxide is 94.8%, and the product selectivity reaches 99.7%.
[0062] Example 7:
[0063] The preparation process and experimental operation steps of Zn-PU are the same as those in Example 3. Replace high-purity CO 2(100%) was replaced with air, and air was continuously introduced during the reaction at a flow rate of 10 mL / min. The reaction time was extended to 40 h. The results showed that the conversion rate of propylene oxide was 66.9%, and the product selectivity reached 99.5%.
[0064] Example 8:
[0065] The preparation process and experimental operation steps of Pd-PU were the same as those in Example 1. Epichlorohydrin was replaced with cyclopentene oxide, and the reaction time was extended to 12 h. The results showed that the conversion rate of cyclopentene oxide was 90.6%, and the product selectivity was 99.1%.
[0066] Example 9:
[0067] The preparation process and experimental operation steps of Pd-PU were the same as those in Example 1. Epichlorohydrin was replaced with 1,2-epoxypropyl bromide, and the reaction time was extended to 10 h. The results showed that the conversion rate of 1,2-epoxypropyl bromide was 96.3%, and the product selectivity was 99.7%.
[0068] Example 10:
[0069] The preparation process and experimental operation steps of Pd-PU were the same as those in Example 1. Epichlorohydrin was replaced with phenyl glycidyl ether, and the reaction time was extended to 18 h. The results showed that the conversion rate of phenyl glycidyl ether was 91.7%, and the product selectivity was 99.0%.
[0070] The specific evaluation results of the catalysts in Examples 1-10 are shown in Table 1 below.
[0071] Table 1 Specific evaluation results of the catalysts in Examples 1-10
[0072]
[0073]
[0074] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A method for preparing a polyurethane-based metal single-atom catalyst, characterized in that: A polyurethane-based metal single atom catalyst with excellent CO2 cycloaddition performance is prepared by anchoring metal single atoms in the polyurethane structure through a simple one-step bonding method. The method comprises the following steps: (1) dissolving an appropriate amount of metal precursor and triethanolamine in an organic reagent to obtain solution A; (2) dissolving an appropriate amount of p-phenylene diisocyanate in an organic reagent to obtain a solution B; (3) Under the protection of inert gas, solution A and solution B are fully mixed and stirred at a constant temperature until gelation occurs, stirring is stopped and the mixture is quickly transferred to a mold for shaping; subsequently, the gel is subjected to a constant temperature aging treatment to further improve its mechanical strength; (4) After the gel aging is completed, the excess organic reagent on the catalyst surface is removed to obtain polyurethane-based metal single atom catalysts M-PU with different shapes; (5) The dried M-PU is placed in a reactor, an appropriate amount of epoxide substrate and a co-catalyst are added, and a gas containing CO2 is continuously introduced to replace the air in the reaction system, and then CO2 and epoxide are cycloaddition-treated under mild conditions to prepare cyclic carbonates. After the reaction is completed, the reaction system is cooled to room temperature, and the M-PU is directly taken out and washed three times with deionized water and anhydrous ethanol to achieve recovery and reuse. The liquid product is qualitatively and quantitatively analyzed by gas chromatography and nuclear magnetic resonance, and the conversion rate of epoxide, the yield and selectivity of the target product cyclic carbonate are further calculated.
2. The method for preparing a polyurethane-based metal single atom catalyst according to claim 1, characterized in that: In step (1), the types of metal precursors include but are not limited to metal oxides, metal chlorides, carbonates, sulfates, and acetates; the types of metals include but are not limited to Au, Ag, Cu, Ni, Pd, Pt, Co, Zn, Ti, Fe, Ru, Mo, Al, and Mg; the concentration of the metal precursor is 0.001 to 1 mol / L; and the concentration of triethanolamine is 0.01 to 10 mol / L.
3. The method for preparing a polyurethane-based metal single atom catalyst according to claim 1, characterized in that: In step (2), the concentration of p-phenylene diisocyanate is 0.01 to 10 mol / L.
4. The method for preparing a polyurethane-based metal single atom catalyst according to claim 1, characterized in that: In steps (1) and (2), the organic reagent includes but is not limited to a mixture of one or more organic reagents, and the types of organic reagents include but are not limited to acetonitrile, tetrahydrofuran, 1,4-dioxane, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and acetone.
5. The method for preparing a polyurethane-based metal single atom catalyst according to claim 1, characterized in that: In step (3), the inert gas includes but is not limited to argon, nitrogen, and helium; the temperature of the constant temperature stirring is 10 to 90°C, the stirring rate is 50 to 1000 rpm, and the stirring time is 5 to 1200 s; the temperature of the constant temperature aging is 10 to 90°C, and the aging time is 1 to 100 h.
6. The method for preparing a polyurethane-based metal single atom catalyst according to claim 1, characterized in that: In step (4), the method of removing the organic solvent on the catalyst surface includes but is not limited to volatilization at room temperature and normal pressure, vacuum drying, forced air drying, and freeze drying; the shape of the catalyst includes but is not limited to block, sheet, strip, and film; the size of the catalyst is 1 to 100,000 cm 2 .
7. The method for preparing a polyurethane-based metal single atom catalyst according to claim 1, characterized in that: In step (5), the types of epoxides include but are not limited to ethylene oxide, propylene oxide, epichlorohydrin, epibromohydrin, styrene oxide, and 1,2-butylene oxide; the types of co-catalysts include but are not limited to tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride, and tetrabutylammonium iodide; the amount of the co-catalyst added is 0.05 to 5.0 mmol; the CO2-containing gas introduced includes but is not limited to high-purity (100%) CO2, low-purity (0.01 to 15%) CO2, air, and industrial flue gas; the mild reaction conditions are low temperature and normal pressure, a temperature of 20 to 100°C, and a reaction time of 2 to 40 hours.
8. A polyurethane-based metal single atom catalyst, characterized in that: The catalyst is prepared by the preparation method according to any one of claims 1 to 7.